Siderite From Minas Gerais, Brazil- Collectors PieceSiderite From Minas Gerais, Brazil Collectors Piece (Stand Included) Weight 70g Size 5cm by 3cm Thickness 1. 5cm Siderite is a mineral composed of iron(II) carbonate. Siderite is both an iron ore and gangue mineral. Its principal economic value lies in its high iron content and the absence of process contaminants such as sulphur or phosphorous. It is part of a large group of isomorphous minerals, the calcite group carbonates, which share similar